Mac DeMarco may no longer need to participate in medical experiments for pocket change, but nine years into his career, the 27-year-old Canadian soft rocker still isn’t taking anything for granted.

“I don’t really set expectations,” he says. “If this is working, then that’s great. But if it’s not, I’ll go get a job at a grocery store. Sometimes you’ve got to pinch yourself, because if you get too used to something that’s this insane, you can end up turning into a jackass.”

Over the course of three albums and assorted other releases, he has found a dedicated following of fans and critics alike, who appreciate his gift for penning songs that float by on a lazy river of woozy guitars and wistful observations. Those same fans are expected to pack the Greek Theatre in Berkeley when he is scheduled to perform, with support from Homeshake and the Garden, on Friday, Sept. 8.

On his latest album, “This Old Dog,” DeMarco’s songwriting has subtly evolved, opting for a cleaner sound that dials back on the effects and allows for a touch of earnestness to creep in. Known for being anything but serious both onstage and off, DeMarco has a changed tone that can be felt in tracks like “My Old Man,” where he makes peace with the hard truth that he might be turning into his father.

Never one to dwell too deeply on questions of process, DeMarco says his approach this time around didn’t vary much from how he’s always done things.

“I don’t really know what I was trying to do,” he says. “I think it was the same approach I take for a lot of things, and especially for making records, which is if I’ve got some time on my hands, I might as well pick up a guitar or whatever and press record.”

In addition to pressing record, DeMarco plays every instrument on “This Old Dog,” in addition to producing and engineering the album. He says the choice to go it alone doesn’t stem from a need to control everything, but is more a reflection of his desire to avoid confrontation.

“I don’t have the balls to like really sit down and work with other people. If something isn’t going well, it’s hard for me to be like, ‘This isn’t quite right,’” he admits. “If I’m doing everything, I can just scrap it when it’s not working.”

In addition to his musical output, DeMarco has built a reputation for having fun and taking it easy, as seen during his recent appearance on Comedy Central’s “@midnight,” a game show that has celebrity contestants lobbing pop-culture-laced zingers at host Chris Hardwick.

“I don’t know how to write jokes. I ended up writing a bunch, but then I got there and it was a lot more relaxed then I thought it would be,” he recalls. “Maybe I just prefer to not really know what’s happening going into stuff like that, to not overthink it.”

Overthinking has never been DeMarco’s style. From daydream ballads to odes pondering the mundane, the course of his music has always been easygoing. While no one gets to where DeMarco is without a sizable amount of effort, he appears content to ride the wave he’s on for as long as it lasts.

“Writing songs and playing shows and making it sound good — that stuff I take seriously,” he says. “But other than that, I’m pretty easygoing. I’m just trying to have a good time.”